Reducing the weight of structural materials can speed up the processing equipment and transports since the acceleration increases for the same amount of energy.

(1)Weight reduction of structural materials

·Iron casting is adopted for columns in the body structure of machine tools. On the other hand, the structural material substitution is becoming popular for reducing the weight of a movable body.

·Structural materials used for machine tools need to have morphological stability, which means that the initial accuracy will not be degraded for a long period of over 10 years. Therefore, certain characteristics are required, such as the homogeneous stability of the material itself and nonexistence of residual stress inside. The required characteristics are summarized here.

(2)Superior vibration damping

·Currently, the following materials are mainly adopted as structural members:

·Each material has its own characteristics.

·Granite has the least specific weight. However, the Young's modulus is so small that it is susceptible to deformation. Adopt an appropriate material as the structural member to avoid deformation.

·Ceramics are the lightweight and strong materials. However, they are extremely difficult to work with. In addition, they are not meant for large-sized products. The exterior panel of a space shuttle is an example of using ceramics in tiles (see [Fig.1]).

·Resin concrete has superior vibration damping but with less structural strength. In Europe, this material has long been adopted in the main units of machine tools.